单项选择题

[听力原文]
W: Why is Bob so tired and worn out
M: He’s been studying day and night for his final term paper! I have warned him many times to prepare earlier, but he would not listen.

What does the man mean()

A.Bob is too tired to study any more.
B.He told Bob not to study late at night.
C.He had often advised Bob to prepare earlier.
D.Bob didn’t hear the warning.